In certain situations, when an airplane is stationary or moving slowly on the ground, it is desired to be able to change the attitude of the airplane, i.e. the angle of inclination of its longitudinal axis and/or its transverse axis.
In document U.S. Pat. No. 5,310,140 in the name of the Applicant, an approach is described consisting in modifying the length of the nosegear without involving the main landing gear. The damper structure described in that document makes it easy to extend the nosegear while the airplane is stationary or moving slowly on the ground, without requiring the hydraulic generator of the airplane to be used, i.e. without it being necessary for the engines to be running.
Document U.S. Pat. No. 5,310,139 in the name of the Applicant describes a nosegear damper designed to perform the same function. Reference can also be made to document GB-A-2,057,629.
The present invention relates more to dampers fitted to vertically-retractable main landing gear for wide-bodied airplanes, comprising a plurality of independent legs arranged one behind another so as to form, in the gear-down position, a row that is parallel to the longitudinal plane of the airplane, with a pair of wheels being mounted at the end of each leg.
Such retractable landing gear for a wide-bodied airplane is described, for example, in documents EP-A-0,676,328 and EP-A-0,614,804 in the name of the Applicant.
In other situations, it is desired to shorten one or more legs when the airplane is stationary or moving slowly on the ground. Such shortening can be advantageous, not only when it is desired to change the attitude of the airplane when stationary, in particular while loading the airplane, but also in other particular situations such as changing a tire or unloading the front leg in order to make turning operations easier. For tire changing it is conventional to use jack systems enabling the structure of the airplane to be raised so as to disengage the tire for changing from its contact with the ground.